Corrosion in Cr-Fe-Co-Ni-Nb hypoeutectic and hypereutectic high entropy alloys

In this paper, corrosion behavior and corresponding mechanism of CrFeCoNiNbx high entropy alloys (HEAs) with hypoeutectic (x = 0.38) and hypereutectic (x = 0.54) structures were systematically investigated. It is found that both HEAs have FCC + Lave dual-phase structure. Similar corrosion behavior could be observed on these HEAs during electrochemical polarization in 3.5 wt% NaCl solution at room temperature, and the hypereutectic HEA shows slightly higher corrosion resistance compared to the hypoeutectic one. Moreover, there are large proportions of Cr+Nb oxides with no significant difference in concentration in the passive films of these HEAs, which has close correlation with their high and similar corrosion resistance. This work provides a novel insight into better understanding of the corrosion mechanism in the Cr-Fe-Co-Ni-Nb HEAs, which is beneficial for their further applications.